1. Field of the Invention
This invention relates to a device and method for protectively coating the print recording surface of an information card such as a credit card and identification card, and more particularly to an information card coating device and method for coating, with a protective film, a card having a recording surface on which information data are printed or recorded.
2. Description of the Prior Art
A variety of types of identification cards (ID cards) such as a license card and a credit card which have been indispensable to social life each have an information recording surface on which information patterns such as the photograph of a cardholder's face, a cardholder's name, and/or a cardholder's identification code number are printed by using a card printer. It is desirable to print, on the recording surface of the card, multiple gradation images such as full-color photographs with dye-sublimation thermal transfer inks, and two-gradation images such as characters with a thermal-wax transfer ink. Anyhow, such information cards must be coated with a protective film for the purpose of protecting the recording surface having information data printed and preventing falsification.
The protective film used as a coating on the information recording surface of the card is generally made of transparent hot-melt plastic film having a thickness of several microns to several ten microns or a high-strength reinforced plastic film with a hot-melt adhesive layer. It is preferable to thermally transfer such a protective reinforced plastic film to the recording surface of the card with heat while being brought into press contact with the card inasmuch as the protective film is fused with heat to merge with the card base, thus to prevent falsification of the card.
The various protective films as mentioned above are formed of materials different in quality and heat characteristic according to the purpose for which the card is used. Furthermore, there is a fair possibility of appearance of new material more suitably applicable to a protective film for information cards. However, the protective films of various types as noted above must not be treated at a fixed temperature.
In a case of using a protective film having a hologram pattern for preventing falsification of the card, a chemical reaction possibly takes place when plasticizing material constituting an adhesive layer of such a hologram protective film comes into touch with the dye-sublimation inks usually used for printing a full-color photographic image on the recording surface of the card, consequently causing diffusion of dye. As a result, possible bleeding of the images printed on the card occurs, as the case may be. In order to surmount the disadvantage, it is necessary to interpose a thin separator film between the recording surface of the card and the hologram film.
It has been desired to affix at least one protective coating film onto the recording surface of the card under the appropriate conditions of thermal-transfer temperature and feeding speed conformable to the material of the protective film so as not to allow the protective film to easily come off the card. Further, the layers of printing inks and the protective films affixed on the card is required not to make conspicuous difference in surface level on the card, which is awkward to touch.